The present invention relates to microstructured components comprising at least one cycloolefin copolymer, to a process for producing these microstructured components, and also to the use of these microstructured components.
DD-A-211 801 and DD-A-211 802 disclose processes for modifying the surface properties of olefin copolymers as semifinished parts and molding materials. The semifinished parts and molding materials comprise ethylene-norbornene copolymer or a combination of ethylene-norbornene copolymer with thermoplastics, fillers, reinforcing materials and plastics auxiliaries. The modification is carried out by treatment with ionizing radiation or by chemical etching. The treatment achieves an improvement in the bondability, printability, metallizability and adhesion of surface coatings to the surface of the semifinished part or molding material. The treatment is carried out at a temperature of from 340 K to 410 K.
It is known from US-A-5,334,424 that the surface roughness of articles based on saturated norbornene resins can be reduced to  less than 0.05 xcexcm by polishing.
Journal of Photopolymer Science and Technology, Volume 10, No. 2 (1997) 159-166, describes processes based on the interaction of laser radiation with polymers.
Y. Nakayama, T. Matsuda in J. Biomed. Res., 29, 1295 (1995) disclose rates of removal of material at an energy flux of 1 J/cm2 using excimer lasers.
It is an object of the present invention to provide microstructured components having a very finely gradated height profile and a very low surface roughness and also to provide an economical and environmentally friendly process for producing microstructured components. For the purposes of the invention, microstructured components are components which have structures in the micron range and below.
The object of the present invention is achieved by microstructured components comprising cycloolefin copolymers.
The microstructured components of the invention comprise at least one cycloolefin copolymer which comprises polymerized units derived from at least one cyclic, in particular polycyclic, olefin and optionally at least one acyclic olefin. The term cycloolefin polymer encompasses both cycloolefin copolymers and cycloolefin homopolymers.
The microstructured components of the invention comprise at least one cycloolefin copolymer comprising from 0.1 to 100% by weight, preferably from 0.1 to 99.9% by weight, based on the total mass of the cycloolefin copolymer, of polymerized units derived from at least one polycyclic olefin of the formula I, II, IIxe2x80x2, III, IV, V or VI 
where R1, R2, R3, R4, R5, R6, R7 and R8 are identical or different and are each a hydrogen atom or a C1-C20-hydrocarbon radical such as a linear or branched C1-C8-alkyl radical, a C6-C18-aryl radical, a C7-C20-alkylenearyl radical, a cyclic or acyclic C2-C20-alkenyl radical or form a saturated, unsaturated or aromatic ring, where identical radicals R1 to R8 in the various formulae I to VI may have different meanings, and n can be from 0 to 5, and from 0 to 99.9% by weight, preferably from 0.1 to 99.9% by weight, based on the total mass of the cycloolefin copolymer, of polymerized units derived from one or more acyclic olefins of the formula VII 
where R9, R10, R11 and R12 are identical or different and are each a hydrogen atom, a linear, branched, saturated or unsaturated C1-C20-hydrocarbon radical such as a C1-C8-alkyl radical or a C6-C18-aryl radical.
In addition, the cycloolefin copolymers used according to the invention for microstructured components may comprise from 0 to 45% by weight, based on the total mass of the cycloolefin copolymer, of polymerized units derived from one or more monocyclic olefins of the formula VIII 
where m is from 2 to 10.
For the purposes of the invention, preference is given to cycloolefin copolymers which comprise polymerized units derived from polycyclic olefins of the formula I or III and polymerized units derived from acyclic olefins of the formula VII.
Particular preference is given to cycloolefin copolymers which comprise polymerized units derived from olefins having a norbornene skeleton, very particularly preferably derived from norbornene and tetracyclododecene and, if desired, vinylnorbornene or norbornadiene. Particular preference is also given to cycloolefin copolymers which comprise polymerized units derived from acyclic olefins having terminal double bonds, e.g. xcex1-olefins having from 2 to 20 carbon atoms, very particularly preferably ethylene or propylene. Exceptional preference is given to norbornene/ethylene and tetracyclododecene/ethylene copolymers.
The cycloolefin copolymers used according to the invention can be prepared at temperatures of from xe2x88x9278 to 200xc2x0 C. and a pressure of from 0.01 to 200 bar in the presence of one or more catalyst systems comprising at least one transition metal compound and optionally a cocatalyst and optionally a support material. Suitable transition metal compounds are metallocenes, in particular stereorigid metallocenes. Examples of catalyst systems which are suitable for preparing the cycloolefin copolymers used according to the invention are described in EP-A407 870, EP-A485 893 and EP-A-503 422. These references are hereby expressly incorporated by reference.
Examples of transition metal compounds used are:
rac-dimethylsilylbis(1 -indenyl)zirconium dichloride,
rac-dimethylgermylbis(1-indenyl)zirconium dichloride,
rac-phenylmethylsilylbis(1-indenyl)zirconium dichloride,
rac-phenylvinylsilylbis(1-indenyl)zirconium dichloride,
1-silacyclobutylbis(1-indenyl)zirconium dichloride,
rac-diphenylsilylbis(1 -indenyl)hafnium dichloride,
rac-phenylmethylsilylbis(1-indenyl)hafnium dichloride,
rac-diphenylsilylbis(1-indenyl)zirconium dichloride,
rac-ethylene-1,2-bis(1-indenyl)zirconium dichloride,
dimethylsilyl-(9-fluorenyl)(cyclopentadienyl)zirconium dichloride,
diphenylsilyl-(9-fluorenyl)(cyclopentadienyl)zirconium dichloride,
bis(1-indenyl)zirconium dichloride,
diphenylmethylene-(9-fluorenyl)cyclopentadienylzirconium dichloride,
isopropylene-(9-fluorenyl)cyclopentadienylzirconium dichloride,
rac-isopropylidenebis(1-indenyl)zirconium dichloride,
phenylmethylmethylene-(9-fluorenyl)cyclopentadienylzirconium dichloride,
isopropylene-(9-fluorenyl)(1-(3-isopropyl)cyclopentadienyl)zirconium dichloride,
isopropylene-(9-fluorenyl)(1-(3-methyl)cyclopentadienyl)zirconium dichloride,
diphenylmethylene-(9-fluorenyl)(1-(3-methyl)cyclopentadienyl)zirconium dichloride,
methyl phenylmethylene(9-fluorenyl)(1-(3-methyl)cyclopentadienyl)zirconium dichloride,
dimethylsilyl-(9-fluorenyl)(1-(3-methyl)cyclopentadienyl)zirconium dichloride,
diphenylsilyl-(9-fluorenyl)(1-(3-methyl)cyclopentadienyl)zirconium dichloride,
diphenylmethylene-(9-fluorenyl)(1-(3-tert-butyl)cyclopentadienyl)zirconium dichloride,
isopropylene-(9-fluorenyl)(1-(3-tert-butyl)cyclopentadienyl)zirconium dichloride,
isopropylene(cyclopentadienyl)(1-indenyl)zirconium dichloride,
diphenylcarbonyl(cyclopentadienyl)(1-indenyl)zirconium dichloride,
dimethylsilyl(cyclopentadienyl)(1-indenyl)zirconium dichloride,
isopropylene(methylcyclopentadienyl)(1-indenyl)zirconium dichloride,
4-(xcex75-cyclopentadienyl)4,7,7-trimethyl-(xcex75-4,5,6,7-tetrahydroindenyl)zirconium dichloride,
[4-(xcex75-cyclopentadienyl)4,7,7-triphenyl-(xcex75-4,5,6,7-tetrahydroindenyl)]zirconium dichloride,
[4-(xcex75-cyclopentadienyl)-4,7-dimethyl-7-phenyl-(xcex75-4,5,6,7-tetrahydroindenyl)]zirconium dichloride,
[4-(xcex75-3xe2x80x2-tert-butylcyclopentadienyl)-4,7,7-triphenyl-(xcex75-4,5,6,7-tetrahydroindenyl)]zirconium dichloride,
[4-(xcex75-3xe2x80x2-tert-butylcyclopentadienyl)-4,7-dimethyl-7-phenyl-(xcex75-4,5,6,7-tetrahydroindenyl)]zirconium dichloride,
[4-(xcex75-3xe2x80x2-methylcyclopentadienyl)4,7,7-trimethyl-(xcex75-4,5,6,7-tetrahydro-indenyl)]zirconium dichloride, 5
[4-(xcex75-3xe2x80x2-methylcyclopentadienyl)-4,7,7-triphenyl-(xcex75-4,5,6,7-tetrahydro-indenyl)]zirconium dichloride, 5
[4-(xcex75-3xe2x80x2-methylcyclopentadienyl)-4,7-dimethyl-7-phenyl-(xcex75-4,5,6,7-tetrahydroindenyl)]zirconium dichloride,
[4-(xcex75-3xe2x80x2-isopropylcyclopentadienyl)4,7,7-trimethyl-(xcex75-4,5,6,7-tetrahydro-indenyl)]zirconium dichloride,
[4(xcex75-3xe2x80x2-isopropylcyclopentadienyl)-4,7,7-triphenyl-(xcex75-4,5,6,7-tetrahydro-indenyl)]zirconium dichloride,
[4-(xcex75-3xe2x80x2-isopropylcyclopentadienyl)4,7-dimethyl-7-phenyl-(xcex75-4,5,6,7-tetrahydroindenyl)]zirconium dichloride,
[4-(xcex75-cyclopentadienyl)(xcex75-4,5-tetrahydropentalene)]zirconium dichloride,
[4-(xcex75-cyclopentadienyl)-4-methyl-(xcex75-4,5-tetrahydropentalene)]zirconium dichloride,
[4-(xcex75-5-cyclopentadienyl)4-phenyl-(xcex75-4,5-tetrahydropentalene)]zirconium dichloride,
[4-(xcex75-cyclopentadienyl)4-phenyl-(xcex75-4,5-tetrahydropentalene)]zirconium dichloride,
[4-(xcex75-3xe2x80x2-methylcyclopentadienyl)(xcex75-4,5-tetrahydropentalene)]zirconium dichloride,
[4-(xcex75-3xe2x80x2-isopropylcyclopentadienyl)(xcex75-4,5-tetrahydropentalene)]zirconium dichloride,
[4-(xcex75-3xe2x80x2-benzylcyclopentadienyl)(xcex75-4,5-tetrahydropentalene)]zirconium dichloride,
[2,2,4-trimethyl-4-(xcex75-cyclopentadienyl)(xcex75-4,5-tetrahydropentalene)]-zirconium dichloride,
[2,2,4-trimethyl4-(xcex75-(3,4-diisopropyl)cyclopentadienyl)(xcex75-4,5-tetrahydropentalene)]zirconium dichloride.
The cycloolefin copolymers are prepared by means of heterogeneous or homogeneous catalysis using organometallic compounds and is described in many patents. Catalyst systems based on mixed catalysts comprising titanium salts and organoaluminum compounds are described in DD-A-109224 and DD-A-237 070. EP-A-156 464 describes the preparation of copolymers using catalysts based on vanadium. EP-A-283 164, EP-A-407 870, EP-A-485 893 and EP-A-503 422 describe the preparation of cycloolefin polymers using catalysts based on soluble metallocene complexes. For the preparative methods and catalyst systems described in these patents for the preparation of cycloolefin copolymers are hereby expressly incorporated by reference.
The cycloolefin copolymers used according to the invention can be prepared by homopolymerization and/or copolymerization of cyclic, preferably polycyclic olefins with retention of the rings.
The cycloolefin copolymers can also be prepared by ring-opening polymerization of at least one of the monomers of the formulae I to VI and subsequent hydrogenation of the products obtained. If desired, the cycloolefin copolymers can also be prepared by ring-opening copolymerization of at least one of the monomers of the formulae I to VI with further monomers, e.g. monocyclic monomers of the formula VIII, and subsequent hydrogenation of the products obtained. The preparation of cycloolefin copolymers is described in the Japanese patents 3-14882, 3-122137, 4-63807, 2-27424 and 2-276842. The preparative methods and catalyst systems described in these patents for the preparation of cycloolefin copolymers are hereby expressly incorporated by reference. Derivatives of these cyclic olefins containing polar groups such as halogen, hydroxyl, ester, alkoxy, carboxy, cyano, amido, imido or silyl groups are likewise included.
The polymerization can also be carried out in a number of stages, in which case block copolymers can also be formed (DE-A42 05 416).
Cycloolefin copolymers are preferably amorphous, transparent materials. The heat distortion resistances of the cycloolefin copolymers can be set within a wide range. The glass transition temperature of cycloolefin copolymers can be employed as an indication of the heat distortion resistance as can be determined on injection-molded specimens in accordance with ISO 75 part 1 and part 2. The cycloolefin copolymers described have glass transition temperatures in the range from xe2x88x9250 to 220xc2x0 C. Preference is given to glass transition temperatures in the range from 0 to 180xc2x0 C., particularly preferably from 40 to 180xc2x0 C.
The mean molar mass of the cycloolefin copolymers can be controlled in a known manner by introduction of hydrogen, variation of the catalyst concentration or variation of the temperature. The cycloolefin copolymers present in the microstructured components of the invention have mass average molar masses Mw in the range from 1 000 to 10 000 000 g/mol. Preference is given to mass average molar masses Mw in the range from 5 000 to 5 000 000 g/mol, particularly preferably from 10 000 to 1 200 000 g/mol.
The cycloolefin copolymers present in the microstructured components of the invention have viscosity numbers in the range from 5 to 1 000 ml/g. Preference is given to viscosity numbers in the range from 20 to 500 ml/g, particularly preferably from 30 to 300 ml/g.
The microstructured components of the invention may also comprise blends of at least one cycloolefin copolymer and at least one further polymer in any mixing ratios.
Preference is given to using the following polymers for the blends with cycloolefin copolymers:
polyethylene, polypropylene, ethylene-propylene copolymers, polybutylene, poly(4-methyl-1-pentene), polyisoprene, polyisobutylene, natural rubber, poly(1-methylene methacrylate), further polymethacrylates, polyacrylate, acrylate-methacrylate copolymers, polystyrene, styrene-acrylonitrile copolymer, bisphenol A polycarbonate, further polycarbonates, aromatic polyester carbonates, polyethylene terephthalate, polybutylene terephthalate, amorphous polyacrylate, nylon 6, nylon 66, further polyamides, polyaramids, polyether ketones, polyoxymethylene, polyoxyethylene, polyurethanes, polysulfones, polyether sulfones, polyvinylidene fluoride.
For blends of cycloolefin copolymers and polyolefins, preference is given to using the following polyolefins: homopolymers of ethylene and propylene and copolymers of these two monomers, copolymers based on ethylene and linear or branched olefins such as butene, pentene, hexene, heptene, octene, nonene, decene, undecene and dodecene, copolymers based on propylene and linear or branched olefins such as butene, pentene, hexene, heptene, octene, nonene, decene, undecene and dodecene, terpolymers of ethylene, propylene and linear or branched olefins such as butene, pentene, hexene, heptene, octene, nonene, decene, undecene and dodecene.
The blends can be produced by customary methods, e.g. by coextrusion of the polymer components from the melt, if desired using further additives, and subsequent granulation.
Cycloolefin copolymers can be processed from the melt or from solution. Suitable solvents are aprotic nonpolar hydrocarbons such as decaline or mixtures of linear and branched hydrocarbons.
The production of the microstructured components of the invention can be carried out by production of the actual component and simultaneous microstructuring, e.g. by thermoplastic processing methods such as injection molding. Also suitable for this purpose is the LIGA process, viz. a combination of lithography, electroforming and molding for producing such microstructured components. Another possibility is microstructuring of the prefabricated component, e.g. by etching processes such as wet chemical etching or dry etching processes, by embossing processes such as hot embossing, by material working by means of laser radiation such as laser ablation using excimer lasers or microwelding, by methods of precision machining such as cutting machining or spark erosion or by photolithography.
It has surprisingly been found that cycloolefin copolymers display particularly low rates of material removal in the production of the microstructured components of the invention by laser ablation. Cycloolefin copolymers are thus surprisingly particularly suitable for microstructured components having very fine profiles. Cycloolefin copolymers are very particularly useful for microstructured components having profiles whose height differences are less than 500 nm.
An important parameter for micromechanical applications is the wall angle xcex1 of the ablated structure. The angle is designated as positive when the area at the bottom of the depression produced is smaller than the area at the surface, and as negative when the circumstances are reversed. Vertical walls are of particular importance in microstructuring. However, positive wall angles are also required since positive wall angles a aid removal from the mold in the replication processes following electroforming.
It has surprisingly been found that cycloolefin copolymers are particularly suitable for microstructured components since both wall angles xcex1=O and positive wall angles can be obtained by selection of appropriate production conditions. Here, cycloolefin copolymers are likewise distinguished from other materials such as PMMA.
The laser ablation of cycloolefin polymers is preferably carried out by means of laser radiation having an energy density of greater than or equal to 1.0 J/cm2, particularly preferably an energy density of greater than or equal to 1.5 J/cm2. To these energy densities, the ablation rate per laser pulse is in the saturation region, i.e. the maximum ablation per laser pulse is achieved. Laser ablation in the saturation region has the advantage that, particularly in the case of energy densities greater than or equal to 1.0 J/cm2, the ablation results achieved are very reproducible and, particularly at energy densities greater than or equal to 1.5 J/cm2, structures having vertical walls are achieved. Low ablation rates can likewise be obtained in laser ablation of conventional polymeric materials such as PMMA, but it is necessary to employ energy densities significantly below the saturation region. This leads to comparatively poorly reproducible ablation results, and also to structures having inclined walls.
In short-wave ultraviolet irradiation of a polymeric material, material is removed from the surface above a critical energy density as a result of photoinduced and thermal decomposition. In laser ablation of cycloolefin polymers, preference is given to using laser radiation having a wavelength of less than or equal to 350 nm. A certain proportion of the ablated material is redeposited on the surface; this material is known as debris.
Microstructured components according to the invention which have been produced by laser ablation surprisingly displayed virtually no debris on examination under a scanning electron microscope and an optical microscope as long as the holes produced had a gap of less than 200 xcexcm. Only in the case of deeper structures were particles having a diameter of less than 100 nm observed in the vicinity of the structures produced. The surface roughness of the microstructured components of the invention is comparatively low, especially on the walls of the structure.
The components produced according to the invention display greatly improved use properties such as low density, high transparency to  less than 300 nm, a high Abbe number, low double refraction, extraordinarily low water absorption, excellent barrier action against water vapor, gradated heat distortion resistance (HDT/B) up to 170xc2x0 C., high stiffness, strength and hardness, little aging under the action of heat or high-energy radiation, good blood compatibility, excellent biocompatibility, good sterilizability by means of hot steam, hot air, ethylene oxide gas and high-energy radiation (gamma radiation and electron beam), very good electrical insulation properties, high resistance to acids, alkalis and polar solvents, good decolorizability and very good thermoplastic processability/flow. Due to the high chemical purity, the microstructured components of the invention are very suitable for applications in microoptics or diffraction optics and for medical and biotechnical components or apparatuses such as capillary electrophoresis. For such applications, the microstructured component has at least one microoptical structure such as a microlens, wave guide or diffraction grating, or at least one fluid-conducting structure such as a capillary channel, sill structure, reaction chamber, mixing structure or filter structure.
Cycloolefin polymers are therefore very particularly suitable for the production of microstructured bodies as prototypes which can be replicated by means of the laser-LIGA technique, cf. Arnold et al., Appl. Surface Sci. 86, 251 (1995). In this method, a layer of a polymer is microstructured by means of laser radiation, with precision machining and/or microengineering processing additionally being able to take place. After application of a thin metal layer to the microstructured surface, a metal or an alloy is electrodeposited in a sufficient thickness. The metallic body which has been deposited in this way can, optionally after surface working, be used as pattern for molding of microstructured bodies in large numbers, for example by means of injection molding using thermoplastic materials.
It has surprisingly been found that cycloolefin copolymers are particularly suitable for microstructured components having a very finely gradated height profile. Cycloolefin copolymers are very particularly useful for microstructured components having fine profiles whose height differences are less than 500 nm. This is of particular interest for the production of elements for diffraction optics whose properties improve with an increasing number of structuring steps. Cycloolefin copolymers are therefore highly suitable for the production of prototypes.
The microstructured components of the invention are suitable for many applications, e.g. in the automobile sector for sensors and regulating systems, in the information and communication sector for systems for optical data transmission and processing, e.g. couplers, connection elements, elements for branching beams and optical switches, for data storages, systems for moving image projection, microlenses, in the medical technology sector for diagnositic systems, atomization systems for inhalers, micropumps for infusion systems, various implants, systems for minimally invasive surgery and in the field of chemical process technology/biotechnology for microreactors, static mixers, pumps, metering systems, filtration systems, valves, etc.
The invention is illustrated by the following examples.